Variações nas concentrações de mercúrio em solos da Reserva Garimpeira do alto rio Madeira

Abstract

Mercury use in the gold mining in the Amazon suffered considerable reductionwhen compared with the decades of 80 and 90. However, Hg levels in fish, and forconsequence, in the local human population, continue to be high. One of the possiblemechanisms responsible for these high Hg concentrations in fish and humans is theremobilization of Hg due to land use changes, in particular deforestation. Thus, theobjective of this work was to evaluate the mercury concentrations contained in soils inthe High Madeira River region verifying the Hg concentrations potentially available forremobilization due to deforestation. For such, soils samples were collected in theregion in areas where the forest was converted to other uses (pasture, agriculture, etc)compared to original forested areas. Deforestation results in physical and chemicalchanges that contribute for the loss of immobilized Hg in forest soils. Deforested soilspresented lower Hg concentrations and burden than forest soils. One of the majorresponsible factors for the Hg loss from converted soils is the reduction of the soilorganic matter. Reduction of throughfall and litterfall also contributed to the lower Hgconcentrations and content in converted soils.